Lubricating oil composition having high dispersancy



2,959,545 LUBRICATING OIL COMPOSITION HAVING HIGH DISPERSANCY Harvey E.Alford, Amherst, Ohio, assignor to The Standard Oil Company, Cleveland,Ohio, a corporation of 'Ohio No Drawing. Filed Dec. 31, 1956, Ser. No.631,507

1 Claim. (Cl. 252-332) This invention relates to a combination oflubricating oil additives having exceptional dispersancy and, moreparticularly, to lubricating oil compositions comprising an alkalinesulfonate detergent and magnesium naphthenate.

For satisfactory performance, a motor oil should contain a dispersant tokeep the insoluble materials which accumulate in the oil in suspension.In the absence of a dispersant, sludge particles agglomerate, pluggingthe oil lines and screens and causing undesirable deposits to separateout on the engine parts. i

In accordance with the invention, lubricating oils having an unusuallyhigh degree of dispersancy are obtained by employing in combination analkaline sulfonate detergent and magnesium naphthenate. Neither of theseadditives by itself is fully satisfactory as a dispersant. Magnesiumnaphthenate alone is not a dispersant at all. However, the two togethergive a powerful synergistic effect.

The preferred alkaline sulfonate detergent is a basic barium sulfonatewhich is prepared from petroleum sulfonic acids having a molecularweight of about 220 to 250 by neutralization with barium oxide orhydroxide. This is mixed in the proportion of to 30 parts by weight(p.b.w.) with 2 to 10 p.b.w. of barium carbonate.

Very small amounts of the additives of the invention will give a markedimprovement in dispersancy. The magnesium naphthenate is present in theoil in an amount within the range from 1% to 7%, and the basic bariumpetroleum sulfonate in an amount from 0.5 to 3%.

The additives of the invention can be used to improve the dispersancy ofany petroleum hydrocarbon oil of lubricating viscosity. The S.A.E.viscosities for lubricating oils range from No. 10 to No. 70. Oilshaving S.A.E. Nos. 10 to 40 have a viscosity within the range from 90 to255 SSU at 130 F., and those oils having S.A.E. Nos. 40 to 70 have aviscosity within the range from 80 to 150 SSU at 210 F. The acid-treatedand solvent-extracted oils are equally useful in the compositions of theinvention. The oils can be blended from suitable bright stocks andfinished neutral oils of light and heavy viscosities. It is impossiblehere to give a complete description of the various methods used in thepreparation of lubricating oils, but reference is made to the text byGeorgi, entitled Motor Oils and Engine Lubrication, published byReinhold Publishing Corporation, New York (1950), chapter V, wherein thevarious types of lubricating oils are discussed fully. Any of the oilsmentioned therein can be employed in the composition of the invention.

The composition of the invention is prepared simply by mixing theadditives either singly or together with the oil, at room temperature.The additives are soluble or dispersible in the oil, and dispersetherein instantaneously. No solvents are required.

The following example represents, in the opinion of the inventor, thebest embodiment of his invention.

nited States. Patent 2 O Patented Nov. 8,

Example A group of lubricating oil compositions were prepared, using alubricating oil blend of 72.5 p.b. volume {solventextracted neutralthermal distillate having a viscosity of 300 SSU at 100 F., and 27.5p.b. volume of a solventextracted bright stock having a viscosity of 78SSU at 210 F.

(1) One lubricating oil composition was made up containing 5.44%magnesium naphthenate to givethe oil an alkaline No. of 12. Themagnesium naphthenate was prepared by direct precipitation from asolution of sodium naphthenate in water, using one equivalent ofmagnesium chloride per equivalent of sodium naphthenate.

(2) Another was prepared containing 1 /2% basic barium petroleumsulfonate. This was a barium petroleum sulfonate prepared from petroleumsulfonic acids having a molecular weight of 235 in an amount of 17.8parts by weight (p.b.w.) mixed with 3.5 p.b.w. of barium carbonate.

(3) and (4) Additional lubricating compositions were prepared containingboth additives in the amounts indicated in the table, in each instance,with an amount of magnesium naphthenate to give the same alkalinenumber. Each of the compositions then was evaluated for dispersancy.

The dispersancy test is a measure of the ability of the oil to holdcarbon black dispersed. The oil to be tested is made up as a 5% solutionthereof in benzene, and 100 ml. of the solution is placed in a glassstoppered graduate. Carbon black in increments of 0.2 gm. is added tothe solution, which is then shaken for fifteen seconds and permitted tostand for five minutes in front of a light source and the contentsobserved for a break point. This point is seen as a thin upper layer ofcompletely transparent liquid containing no carbon black particles. Ifno break point is observed, additional increments of carbon black areadded until there is a break point. The largest amount of carbon blackwhich does not produce a break point is recorded as the result of thetest. The test has been calibrated against various additiveconcentrations of dispersant additives in oil and is a measure of thedispersant or detergent properties of an oil.

The results are shown in the following table:

The synergistic effect of the magnesium naphthenate in combination withthe barium sulfonate is evident from the table. The rating of 6.8 to 8.0in Nos. 3 and 4 is far superior to the ratings of either of theseadditives by themselves (Nos. 1 and 2), which range from 3.6 to 0, andthese superior values are obtained using less of each additive.

Other modifications will be obvious to one skilled in the art and theseare intended to be included within the scope of the following claims:

I claim:

A mineral lubricating, oil composition exhibiting improved dispersancyconsisting of from to 98.5% mineral oil and from 1.5 to 10% of anadditive containing from 0.5 to 3 parts by weight basic barium petroleumsulfonate and from 1 to 7 parts by weight magnesium 2,415,353

naphthenate. 2,560,202 2,606,872

References Cited in the file of this patent UNITED STATES PATENTS 52,228,500 Bergstrom 13111.14, 1941 2,322,307 Neely et a1 -JLJune 22,1943 4 Johnson et a1. Feb. 4, 1947 Zimmer et a1. July 10, 1951 Gasser eta1 Aug. 12, 1952 OTHER REFERENCES Motor Oils and Engine Lubrication,Georgi, Reinhold Pub. Co., New York (1950), pp. 169-176.

